July 11th: At today's All-Star Game media session, Fielder was asked about the DH possibility again and offered additional comments to WEEI's Alex Speier. Speier says Fielder "suggested that he will listen to offers from clubs that see him as a designated hitter," though the slugger noted the difficulty of the adjustment.
June 29th: First baseman Prince Fielder wouldn't rule out signing as a DH, talking to John Harper of the New York Daily News:
"I'm not ruling anything out, but as for right now, I like playing first base."
Admittedly, that's a tiny scrap of information, but Fielder has been understandably reluctant to talk in-depth about his upcoming free agency. It is notable that Fielder didn't openly rule out the possibility of signing as a designated hitter. Of course, the best offer often trumps the player's preference, as we saw with Adam Dunn and the White Sox last offseason.
Harper's article discusses the possibility of the Yankees signing Fielder to DH, since first base will be occupied by Mark Teixeira through 2016. The Red Sox could technically consider Fielder as a DH as well, but both scenarios seem highly unlikely for plenty of reasons. Surely Scott Boras would prefer those teams in the mix for his client. But we're talking about what Boras hopes to be the third-largest contract in baseball history, so Fielder will probably not ditch his glove in the first year.